Local adaptation with gene flow in a highly dispersive shark.

Adaptive divergence in response to environmental clines are expected to be common in species occupying heterogeneous environments. Despite numerous advances in techniques appropriate for non-model species, gene-environment association studies in elasmobranchs are still scarce. The bronze whaler or copper shark (Carcharhinus brachyurus) is a large coastal shark with a wide distribution and one of the most exploited elasmobranchs in southern Africa. Here, we assessed the distribution of neutral and adaptive genomic diversity in C. brachyurus across a highly heterogeneous environment in southern Africa based on genome-wide SNPs obtained through a restriction site-associated DNA method (3RAD). A combination of differentiation-based genome-scan (outflank) and genotype-environment analyses (redundancy analysis, latent factor mixed models) identified a total of 234 differentiation-based outlier and candidate SNPs associated with bioclimatic variables. Analysis of 26,299 putatively neutral SNPs revealed moderate and evenly distributed levels of genomic diversity across sites from the east coast of South Africa to Angola. Multivariate and clustering analyses demonstrated a high degree of gene flow with no significant population structuring among or within ocean basins. In contrast, the putatively adaptive SNPs demonstrated the presence of two clusters and deep divergence between Angola and all other individuals from Namibia and South Africa. These results provide evidence for adaptive divergence in response to a heterogeneous seascape in a large, mobile shark despite high levels of gene flow. These results are expected to inform management strategies and policy at the national and regional level for conservation of C. brachyurus populations.

Comparative analyses of the complete mitochondrial genomes of two southern African endemic guitarfish, Acroteriobatus annulatus and A. blochii.

Shark-like rays (order Rhinopristiformes) are among the most threatened cartilaginous fish globally. Despite this, unresolved taxonomic issues still exist within the group. To date, no studies have used complete mitochondrial genomes to assess the phylogenetic placement of Acroteriobatus within the non-monophyletic family Rhinobatidae. The current study reports the first complete mitochondrial genomes for Acroteriobatus annulatus and A. blochii. Similar to other rhinopristiforms, the complete sequences of A. annulatus (16,773 bp) and A. blochii (16,771 bp) were circular molecules with gene organisations identical to that of the typical vertebrate mitogenome. The A + T content was higher than the G + C content, with a bias towards A and C nucleotides observed in all complete mitogenomes. The stem-and-loop secondary structures of the putative origin of light-strand replication were found to have highly conserved synthesis and stem regions, with all substitutions and indels restricted to the loop structure. The ratios of non-synonymous to synonymous substitution rates indicated that purifying selection has been the dominant driver of evolution in rhinopristiform mitogenomes. Phylogenetic reconstructions placed Acroteriobatus as a sister-group to Rhinobatos, confirming its affiliation with the family Rhinobatidae. However, based on its apparent polyphyly with the aforementioned genera, the familial assignment of Pseudobatos is not fully resolved and requires further investigation.

Site fidelity and shallow genetic structure in the common smooth-hound shark Mustelus mustelus confirmed by tag-recapture and genetic data.

The common smooth-hound shark, Mustelus mustelus, is a widely distributed demersal shark under heavy exploitation from various fisheries throughout its distribution range. To assist in the development of appropriate management strategies, the authors evaluate stock structure, site fidelity and movement patterns along the species' distribution in southern Africa based on a combination of molecular and long-term tag-recapture data. Eight species-specific microsatellite markers (N = 73) and two mitochondrial genes, nicotinamide adenine dehydrogenase subunit 4 and control region (N = 45), did not reveal any significant genetic structure among neighbouring sites. Nonetheless, tagging data demonstrate a remarkable degree of site fidelity with 76% of sharks recaptured within 50 km of the original tagging location. On a larger geographic scale, dispersal is governed by oceanographic features as demonstrated by the lack of movements across the Benguela-Agulhas transition zone separating the South-East Atlantic Ocean (SEAO) and South-West Indian Ocean (SWIO) populations. Microsatellite data supported very shallow ocean-based structure (SEAO and SWIO) and historical southward gene flow following the Agulhas Current, corroborating the influence of this dynamic oceanographic system on gene flow. Moreover, no movements between Namibia and South Africa were observed, indicating that the Lüderitz upwelling formation off the Namibian coast acts as another barrier to dispersal and gene flow. Overall, these results show that dispersal and stock structure of M. mustelus are governed by a combination of behavioural traits and oceanographic features such as steep temperature gradients, currents and upwelling systems.

Cargas de trabalho e desgastes dos trabalhadores de enfermagem em serviços de medicina nuclear do brasil

RESUMO Objetivo: Identificar as cargas de trabalho geradoras de desgastes em trabalhadores de enfermagem em dois Serviços de Medicina Nuclear (SMN) localizados na região sul do Brasil. Material e Método: Trata-se de pesquisa qualitativa, pautada na Psicodinâmica do Trabalho, que investigou 12 trabalhadores de enfermagem atuantes em dois SMN, um público e um privado. Os dados foram organizados com o auxílio do software QualiQuantSoft® e interpretados por meio da análise do discurso do sujeito coletivo. Resultados: Os trabalhadores pesquisados estão expostos às cargas de trabalho de materialidade interna e externa. As cargas de trabalho biológicas, físicas, mecânicas, fisiológicas e psíquicas foram fortemente representadas nos discursos dos trabalhadores. Essas cargas são responsáveis por desgastes que se manifestam em dores lombares, problemas osteoarticulares, fadiga e desgastes psíquicos. Os desgastes evidenciados estão diretamente relacionados à natureza e intensidade das cargas de trabalho no cotidiano do profissional. Conclusão: Na medicina nuclear observa-se a sobreposição das cargas de trabalho inerentes a organização e as especificidades da atividade laboral. As cargas de trabalho se manifestam, principalmente, quanto ao uso da radiação ionizante, sendo que os desgastes impactam no corpo do trabalhador em manifestações físicas e psíquicas. A enfermagem, enquanto categoria, deve ser empoderada de forma mais assertiva dessa especialidade através de educação continuada e pesquisas sobre a temática, pois trata-se de uma área de atuação em expansão para esses profissionais.

ABSTRACT Objective: To identify the workloads that generate exhaustion in nursing workers of two Nuclear Medicine Services (NMS) located in southern Brazil. Material and Method: Qualitative research, based on the Psychodynamics of Work, which focused on 12 nursing workers at two NMS, one public and one private. The data were organized using the QualiQuantSoft® software and interpreted through the analysis of the discourse of the collective subject. Results: The surveyed workers are exposed to workloads of internal and external materiality. The biological, physical, mechanical, physiological and psychological workloads were strongly represented in the workers' discourses. These loads are responsible for exhaustion that is manifested in low back pain, osteoarticular problems, fatigue and psychological stress. The stress shown is directly related to the nature and intensity of workloads in the professional's daily life. Conclusion: In the field of nuclear medicine, there is an overlapping of workloads that is inherent to the organization and specificities of the work activity. Workloads are manifested mainly in the use of ionizing radiation, and the resulting exhaustion affects the worker's body with physical and psychological symptoms. Nursing, as a category, should be more assertively involved in this specialty through continuing education and research on the subject, as it is an expanding area of activity for nursing professionals.

RESUMEN Objetivo: Identificar las cargas de trabajo que generan desgaste en el personal de enfermería de dos Servicios de Medicina Nuclear (SMN) ubicados al sur de Brasil. Material y Método: Se trata de una investigación cualitativa, basada en la Psicodinámica del Trabajo, que investigó a 12 trabajadores de enfermería que trabajan en dos SMN, uno público y otro privado. Los datos fueron organizados con la ayuda del software QualiQuantSoft® e interpretados a través del análisis del discurso del sujeto colectivo. Resultados: Los trabajadores encuestados están expuestos a cargas de trabajo de materialidad interna y externa. Las cargas de trabajo biológicas, físicas, mecánicas, fisiológicas y psicológicas estuvieron fuertemente representadas en los discursos de los trabajadores. Estas cargas son las responsables del desgaste que se manifiesta en lumbalgia, problemas osteoarticulares, fatiga y desgaste psicológico. El estrés encontrado está directamente relacionado con la naturaleza e intensidad de las cargas de trabajo en la vida diaria del profesional. Conclusión: En medicina nuclear existe una superposición de cargas de trabajo inherentes a la organización y especificidades de la actividad laboral. Las cargas de trabajo se manifiestan, principalmente, en el uso de radiaciones ionizantes y el desgaste impacta en el cuerpo del trabajador con manifestaciones físicas y psicológicas. Enfermería, como categoría, debe empoderarse de manera más asertiva en esta especialidad a través de la educación continua y la investigación sobre el tema, por ser, para estos profesionales, un área de actividad en expansión.

New polymorphic microsatellite loci revealed for the dusky shark Carcharhinus obscurus through Ion Proton double-digest RAD sequencing.

The non-model shark species, dusky shark Carcharhinus obscurus, is a bio-economically and recreationally important shark in many areas of its range. Despite of the fishery importance of C. obscurus few genetic resources are currently available for the species. Here, we report on the isolation of eight novel microsatellite loci from C. obscurus using a double-digest restriction site associated DNA (RAD) sequencing approach on the Ion Proton semiconductor platform (ddRADseq-ion). We characterised the loci in 26 individuals and all loci were polymorphic, exhibiting 5-10 alleles (average 6.6), and observed and expected heterozygosities of 0.385-0.962 and 0.479-0.847, respectively. We found that all pairs of loci were in linkage equilibrium and conformed to Hardy-Weinberg expectations. The loci reported in this study are only the second set of microsatellite loci ever characterized for C. obscurus and will be valuable for molecular ecology studies for this vulnerable species.

Population genetics of Southern Hemisphere tope shark (Galeorhinus galeus): Intercontinental divergence and constrained gene flow at different geographical scales.

The tope shark (Galeorhinus galeus Linnaeus, 1758) is a temperate, coastal hound shark found in the Atlantic and Indo-Pacific oceans. In this study, the population structure of Galeorhinus galeus was determined across the entire Southern Hemisphere, where the species is heavily targeted by commercial fisheries, as well as locally, along the South African coastline. Analysis was conducted on a total of 185 samples using 19 microsatellite markers and a 671 bp fragment of the NADH dehydrogenase subunit 2 (ND2) gene. Across the Southern Hemisphere, three geographically distinct clades were recovered, including one from South America (Argentina, Chile), one from Africa (all the South African collections) and an Australia-New Zealand clade. Nuclear data revealed significant population subdivisions (FST = 0.192 to 0.376, p<0.05) indicating limited gene flow for tope sharks across ocean basins. Marked population connectivity was however evident across the Indian Ocean based on Bayesian clustering analysis. More locally in South Africa, F-statistics and multivariate analysis supported moderate to high gene flow across the Atlantic/Indian Ocean boundary (FST = 0.035 to 0.044, p<0.05), with exception of samples from Struisbaai and Port Elizabeth which differed significantly from the rest. Discriminant and Bayesian clustering analysis indicated admixture in all sampling populations, decreasing from west to east, corroborating possible restriction to gene flow across regional oceanographic barriers. Mitochondrial sequence data recovered seven haplotypes (h = 0.216, π = 0.001) for South Africa, with one major haplotype shared by 87% of the individuals and at least one private haplotype for each sampling location except Port Elizabeth. As with many other coastal shark species with cosmopolitan distribution, this study confirms the lack of both historical dispersal and inter-oceanic gene flow while also implicating contemporary factors such as oceanic currents and thermal fronts to drive local genetic structure of G. galeus on a smaller spatial scale.

World without borders-genetic population structure of a highly migratory marine predator, the blue shark (Prionace glauca).

Highly migratory, cosmopolitan oceanic sharks often exhibit complex movement patterns influenced by ontogeny, reproduction, and feeding. These elusive species are particularly challenging to population genetic studies, as representative samples suitable for inferring genetic structure are difficult to obtain. Our study provides insights into the genetic population structure one of the most abundant and wide-ranging oceanic shark species, the blue shark Prionace glauca, by sampling the least mobile component of the populations, i.e., young-of-year and small juveniles (<2 year; N = 348 individuals), at three reported nursery areas, namely, western Iberia, Azores, and South Africa. Samples were collected in two different time periods (2002-2008 and 2012-2015) and were screened at 12 nuclear microsatellites and at a 899-bp fragment of the mitochondrial control region. Our results show temporally stable genetic homogeneity among the three Atlantic nurseries at both nuclear and mitochondrial markers, suggesting basin-wide panmixia. In addition, comparison of mtDNA CR sequences from Atlantic and Indo-Pacific locations also indicated genetic homogeneity and unrestricted female-mediated gene flow between ocean basins. These results are discussed in light of the species' life history and ecology, but suggest that blue shark populations may be connected by gene flow at the global scale. The implications of the present findings to the management of this important fisheries resource are also discussed.

Species identification and comparative population genetics of four coastal houndsharks based on novel NGS-mined microsatellites.

The common smooth-hound (Mustelus mustelus) is the topmost bio-economically and recreationally important shark species in southern Africa, western Africa, and Mediterranean Sea. Here, we used the Illumina HiSeq™ 2000 next-generation sequencing (NGS) technology to develop novel microsatellite markers for Mustelus mustelus. Two microsatellite multiplex panels were constructed from 11 polymorphic loci and characterized in two populations of Mustelus mustelus representative of its South African distribution. The markers were then tested for cross-species utility in Galeorhinus galeus, Mustelus palumbes, and Triakis megalopterus, three other demersal coastal sharks also subjected to recreational and/or commercial fishery pressures in South Africa. We assessed genetic diversity (NA, AR, HO, HE, and PIC) and differentiation (FST and Dest) for each species and also examined the potential use of these markers in species assignment. In each of the four species, all 11 microsatellites were variable with up to a mean NA of 8, AR up to 7.5, HE and PIC as high as 0.842. We were able to reject genetic homogeneity for all species investigated here except for T. megalopterus. We found that the panel of the microsatellite markers developed in this study could discriminate between the study species, particularly for those that are morphologically very similar. Our study provides molecular tools to address ecological and evolutionary questions vital to the conservation and management of these locally and globally exploited shark species.